For any given positive integer n ≥ 1, the Euler function φ（n） is defined to be the number of positive integers not exceeding n, which is relatively prime to n. o：（n） is defined to be the number of different pri...For any given positive integer n ≥ 1, the Euler function φ（n） is defined to be the number of positive integers not exceeding n, which is relatively prime to n. o：（n） is defined to be the number of different prime divisors of n. In order to know the solvability of the function of φ（φ（φ（n））） = 2^ω（n）, properties of the number theoretical function φ（φ（n）） is studied in the paper.展开更多
In this paper, the authors consider the expansion problem of a wedge of gas into vacuum for the two-dimensional Euler equations in isothermal flow. By the bootstrapping argument, they prove the global existence of the...In this paper, the authors consider the expansion problem of a wedge of gas into vacuum for the two-dimensional Euler equations in isothermal flow. By the bootstrapping argument, they prove the global existence of the smooth solution through the direct method in the case 0 〈 θ 〈 -θ=arctan 1/（√2＋√5）, where θ is the half angle of the wedge. Furthermore, they get the uniform C^1,1 estimates of the solution to the expansion problem.展开更多
In this paper, a fractional-order model which describes the human immunodeficiency type-1 virus （HIV-1） infection is presented. Numerical solutions are obtained using a generalized Euler method （GEM） to handle the...In this paper, a fractional-order model which describes the human immunodeficiency type-1 virus （HIV-1） infection is presented. Numerical solutions are obtained using a generalized Euler method （GEM） to handle the fractional derivatives. The fractional derivatives are described in the Caputo sense. We show that the model established in this paper possesses non-negative solutions. Comparisons between the results of the fractional-order model, the results of the integer model and the measured real data obtained from 10 patients during primary HIV-1 infection are presented. These compar- isons show that the results of the fractional-order model give predictions to the plasma virus load of the patients better than those of the integer model.展开更多
In this article, we discuss a numerical method for the computation of the minimal and maximal solutions of a steady scalar Eikonal equation. This method relies on a penalty treatment of the nonlinearity, a biharmonic ...In this article, we discuss a numerical method for the computation of the minimal and maximal solutions of a steady scalar Eikonal equation. This method relies on a penalty treatment of the nonlinearity, a biharmonic regularization of the resulting variational problem, and the time discretization by operator-splitting of an initial value problem associated with the Euler-Lagrange equations of the regularized variational problem. A low-order finite element discretization is advocated since it is well-suited to the low regularity of the solutions. Numerical experiments show that the method sketched above can capture efficiently the extremal solutions of various two-dimensional test problems and that it has also the ability of handling easily domains with curved boundaries.展开更多
基金the National Natural Science Foundation of China(10671056)
文摘For any given positive integer n ≥ 1, the Euler function φ（n） is defined to be the number of positive integers not exceeding n, which is relatively prime to n. o：（n） is defined to be the number of different prime divisors of n. In order to know the solvability of the function of φ（φ（φ（n））） = 2^ω（n）, properties of the number theoretical function φ（φ（n）） is studied in the paper.
基金supported by the National Natural Science Foundation of China(No.11371240)Shanghai Municipal Education Commission of Scientific Research Innovation Project(No.11ZZ84)+1 种基金the Fundamental Research Funds for the Central Universities(No.15CX02074A)the grant of “the First-Class Discipline of Universities in Shanghai”
文摘In this paper, the authors consider the expansion problem of a wedge of gas into vacuum for the two-dimensional Euler equations in isothermal flow. By the bootstrapping argument, they prove the global existence of the smooth solution through the direct method in the case 0 〈 θ 〈 -θ=arctan 1/（√2＋√5）, where θ is the half angle of the wedge. Furthermore, they get the uniform C^1,1 estimates of the solution to the expansion problem.
文摘In this paper, a fractional-order model which describes the human immunodeficiency type-1 virus （HIV-1） infection is presented. Numerical solutions are obtained using a generalized Euler method （GEM） to handle the fractional derivatives. The fractional derivatives are described in the Caputo sense. We show that the model established in this paper possesses non-negative solutions. Comparisons between the results of the fractional-order model, the results of the integer model and the measured real data obtained from 10 patients during primary HIV-1 infection are presented. These compar- isons show that the results of the fractional-order model give predictions to the plasma virus load of the patients better than those of the integer model.
基金supported by the National Science Foundation(No.DMS-0913982)
文摘In this article, we discuss a numerical method for the computation of the minimal and maximal solutions of a steady scalar Eikonal equation. This method relies on a penalty treatment of the nonlinearity, a biharmonic regularization of the resulting variational problem, and the time discretization by operator-splitting of an initial value problem associated with the Euler-Lagrange equations of the regularized variational problem. A low-order finite element discretization is advocated since it is well-suited to the low regularity of the solutions. Numerical experiments show that the method sketched above can capture efficiently the extremal solutions of various two-dimensional test problems and that it has also the ability of handling easily domains with curved boundaries.
